Apparatus for the stabilization of free-piston machines



Jan. 5, 1960 E. A. wAcHsMUTH 2,919,635

APPARATUS FOR THE STABILIZTION OF' FREE-PISTON MACHINES Filed Aug. 24, 1955 6 Sheets-Sheet 1 Jan- 5, 1960 E. A. WACHSMUTH 2,939,685

APPARATUS FOR THE STABILIZATION OF' FREE-PISTON MACHINES Filed Aug. 24, 1955 6 Sheets-Sheet 2 Jam 5, 1950 E. A. wAcHsMUTH 2,919,535

APPARATUS FOR THE STABILIZATION OF FREE-PISTON MACHINES Filed Aug. 24, 1955 6 Sheets-Sheet 3 'W W 94/02 ij fL 'fi-3 V93/00 g3 Eiga. f A i g i A 97 /07 /20 Jan. 5, 1960 E. A. wAcHsMu'rH 2,919,685

APPARATUS FOR THE STABILIZATION 0F FREE-PISTON MACHINES Filed Aug. 24, 1955 6 Sheets-Sheet 4 Jan- 5, 1960 E. A. wAcHsMuTH 2,919,585

APPARATUS FOR THE STABILIZATION OF' FREE-PISTON MACHINES Filed Aug. 24, 1955 6 Sheets-Sheet 5 Jan- 5, 1960 l E. A. wAcHsMUTH 2,919,585

APPARATUS FOR THE STABILIZATION OF' FREE-PISTON MACHlNES Filed Aug. 24, 1955 6 Sheets-Sheet 6 f? 172g l my 6/ 2 V Mmmm@ fflllllllllgllglglellullrllllgl l l @Egli/lm@ lll/5171;:

United States Patent C) APPARATUS FOR THE STABILIZATION F FREE-PHSTN MACHINES Erich A. Wachsmuth, Michigan City, Ind., assigner to Joy Manufacturing Company, Pittsburgh, Pa., a corporation of Pennsylvania Application August 24, 1955, Serial No. 530,246

18 Claims. (Cl. 1233-46) This invention relates in a primary aspect to free-piston, internal combustion engine-driven compressors, and more particularly to apparatus for stabilizing the operation of such machines. More especially, from this aspect, the invention relates to apparatus for stabilizing machines of the character mentioned in which two opposed-piston systems are arranged and connected in counterstroke relation to each other, i.e. with the pistons of one system traveling in the opposite direction to the corresponding pistons of the other system. From another aspect it relates to improvements in fuel injection apparatus for internal combustion engines. Other aspects may hereinafter be noted.

The stabilizing of free-piston machines of the type in n which two motor-compressor units, each of the opposedpiston type, are coupled together', for example mechanically or hydraulically, in such relation to each other that the reciprocating elements of one unit make their working strokes while the reciprocating elements of the other unit are moved through their opposite strokes, is more dicult than the stabilizing of a free-piston mechanism which comprises but one pair of motor-compressor pistons. The necessity which characterizes all freepiston machines, that there be a balance within each stroke between the energy available for drive and the energy absorbed by the compressor, is particularly critical in machines embodying two motor-compressor units as above mentioned, in lview of the but slight differences in stroke length which are permissible with such machines.

In contrast with machines which comprise but one pair of motor-compressor pistons, in which machines, independent of the load condition of the machine, each time there is an excess of energy in the motor, it is automatically used up in useful work in the compressor, with resultant immediate reduction in the energy available for effecting the return piston stroke which effects compression in the motor (whereby the tendency of such machines to run away is overcome or at least greatly reduced), in machines of the two-opposed-piston-systemstype each excess of energy in the motor end-and this is particularly so during running without load-leads, under a constant increase of the stroke, to a rapid increase in the rate of operation, and, as a result, these machines have a tendency to instability. Such an excess of motor energy can result from a change in load upon the machine while it is running, with the result that the characteristic of fuel injection pumps of the groovecontrolled type to increase the injection pressure as the frequency of injections increases, makes the machine still more unstable when such pumps are used.

The present invention solves the stabilizing problem of such machines in a simple manner-namely that-independent of the load condition of the machine-upon each exceeding of the normal stroke of the working piston the pressure line system of the fuel injection pump is more or less relieved, depending upon the amount of overstroking, in such a manner that, without change in the dis- Patented Jan. 5, 196()l placement of the fuel pump, the quantity of fuel delivered to the motor is diminished as the motor piston stroke increases.

The relieving mentioned may desirably be effected inside the injection pump itself, as by the employment of the pump plunger itself as an impulse giver, for example to the pump discharge valve, or by the provision of a small hole connected with the system behind (beyond) the delivery (pump discharge) valve and maintained closed by the pump plunger as long as the machine is not exceeding its minimum stroke, but adapted, when the minimum stroke is exceeded, to permit the escape of a closely controlled amount of fuel to the suction chamber of the pump, the amount so escaping regulated by thc degree of plunger movement beyond that which corresponds to minimum stroke.

In the practice of the invention it is desirable that there be used an injection system which normally works without, or with only a slight, relief of the pressure within the system at the end of fuel discharge, for example, the employment of a pressure valve without any special relief device (as, for example, a relief piston) and the use of an injection nozzle causing either no-or only a slight-relief wave.

The next item here to be noted can most readily be appreciated if a series of denitions be attempted. Accordingly the term normal stroke will be adopted to designate that stroke which is relatively constantly maintained when the machine is operating under a relatively constant load and with the deviations from normal air demand at a minimum so that receiver pressure remains relatively constant. Maximum stroke will be used to indicate that stroke, greater than normal stroke, beyond which, in a given design, there might occur mechanical engagement of the relatively reciprocable chamber-forming or bounding parts of the machine. And minimum stroke will be employed to identify that stroke length below which, under normal load, the apparatus would not maintain operation.

Now it may be seen that there are at least two possibilities. There may be automatic regulation of stroke length operative only when normal stroke length is eX- ceeded; and there may be automatic regulation which extends throughout the whole range of variation in stroke length from minimum to maximum. The second is the more advantageous in that it will not only diminish the injected amount of fuel caused by overstroke (stroke above normal) but also increase the amount of injected fuel beyond its normal amount in case of understroke (stroke less than normal) The first type of automatic regulation is valuable, in that it diminishes the A `ish the fuel in case of overstroke.

As has been suggested above, automatic regulation may very readily be effected through mechanical coaction between the fuel pump plunger and the pump discharge valve.

When the automatic regulation is to be effected only above normal stroke, the increase in the stroke of the pump plunger which attends the exceeding by the motor piston of normal stroke may be caused to push openreopen-the fuel pump discharge Valve which had already closed, whereby there may be a relief of the stillunder-pressure conduit system between the fuel injection pump and the nozzle, back towards the working chamber of the pump, which chamber is vented at the end of the pumping stroke. The extent of the thus-effected relief can be influenced by appropriate choice of the injection nozzle, the selection vof nozzle opening and closing pressures, the suitable determination of the volume of the conduit beyond the fuel injection pump discharge valve, and by the provision of a check valve suitably arranged the conduit between the fuel injection pump and the nozzle. The coaction between the fuel pump and the discharge valve, when control of the latt .l expedient resorted to in the practice of the inventi n. .l be accomplished through the use of a thrust pin, pref ably integral either with the pump discharge va or pump plunger, and when above-normal automc lation only is to be effected by such arrangemeA of such length that upon exceeding of the normal stroke of the pump plunger it unseats and pushes open the pump discharge valve.

It is advisable in order to effect regulation of the quantity of fuel pumped while the apparatus is partially loaded, to use an injection pump with variable commence ment but with termination-fixed fuel displacement. ln an appropriately designed pressure supply system. such a pump, with its discharge of fluid on each stroke ending at a fixed point near the dead point of the unit, re rdlcss of the injection pressure. makes possible, wien the n chine is operating unloaded. the continuation of injection, in small quantities, of fuel beyond the normal derd point of the machine. Accordingly, the commencement of relief during the actual period of injection may red'- the quantity of fuel delivered to the motor7 and the desired decrease in stroke length may be immediately effected.

When the wider range of automatic control viously referred to is desired-as may normally be tl`A case-rand it is wished not only to diminish the injected amount of fuel caused by overstroke, but also to in se it beyond its normal amount in case of understroke. tl .s may be accomplished, in an apparatus as just described.y by providing a thrust pin of such length that the pun-.p dlsc a valve begins to be opened mechanically as socn as the piston stroke of the apparatus commences to grow the minimum length at which the machine is ahi crate, ln an apparatus so arranged, the whole d amount of fuel from the fuel pump may vary as follows: at minimum stroke, ll0% of not consumption; at normal stroke, 100% of fuel consumption, and at maximum stroke, normal fuel consumption.

The effecting of stroke regulation by other ments than means coacting mechanically with pump discharge valve is mentioned above. instead opening the delivery (pump discharge) valve by the pus of the fuel pump plunger, this plunger may be ci to control a small hole connected with the fuel delivering system behind, that is, towards the injection nozzlc from, the delivery valve, and having this hole and the plunger so arranged that the hole is closed by the unger as long as the machine is not exceeding its minimum stroke. When that stroke is exceeded, the plunger uncovers the control hole more or less, or for a greater or lesser period depending on the length of its stroke, which related to the stroke length of the machine. periods when the hole is opened. a very closely c`l amount of fuel escapes through the hole to the chamber of the pump, whereby it is driven out by the combustion pressure in case an open nozzle is being employed, or by the remaining pressure in the system case a closed nozzle is being employed. This e pcd amount of fuel has to be replaced by the next delivery stroke of the pump plunger before the injection start, winch means that the next injected amount of fuel is smaller by this lost portion.

ln view of the hunting characteristic of position of the control hole will desirably that for the minimum stroke with which t.

pre

pron weer Wippen; at

, sation, and et maxi As will hereinafter be explained and illustrated, the different moes of fuel control can be re `dily embodied `nation with injection pun ps of the accumulator disclosed 'rake it possible to n dead point and ction, that is, and not two liv/hi le in much of what has been said the peculiar ads of the invention in machines in which two motorin ch of the opposed piston type, are t the reciprocating elements of one strokes while the reciprocating are thr ugh their opkcs, it is not to supposed that the present inwithout utility in machines which employ but r of motoncompressor p n ui le present invention is to provide an 'agement for free-piston macfrdi is variable during operation, oved free-piston cngine-compresmeans for maintaining stabilized 'c ely correcting deviations from *Another obiect of the invention is to .fide an improved motor-compressor, particularly one "luding two su y connected motor-compressor syscreh Compri g two motor-compressor units with ng pi. .ons of the two systems moving h other, such motor-compressor incormeans for stabilizing its operation. is to provide an improved fuel pumping fuel jection type of motor. A still the invention is to provide an improved iatus for a freeipiston motor operated from normal operation are another is to provide 113mg apparatus for a free-piston motor for the prompt correction of overstrokfurther object is to provide improved a us for the purpose set forth which shall Shout the entire operating range from to maximum stroke. Another oban improved fuel pumping unit for ed in which auto- 3i) stro ouV stroke t ,rs, for e. coa' valve, or the pump plu er and barrel, or As ct1n r o7 ts will appear as the invention ferent illustrative embodi- "iew in central some -arts in elevation,

y he embodied in its more comprehensive aspects Lor-c mpressor which the invention' 5, and'in which in its fuel pump aspects it may be incorporated.

Fig. 2 is a diagrammatic view illustrating one form of automatic controlling apparatus for the twin motorcompressor illustrated in Fig. l.

Fig. 3 shows on an enlarged scale the pump cylinder of a fuel injection pump, showing the pump plunger, the pump discharge valve, and one thrust pin arrangement for causing relief of uid from the injection system in accordance with one embodiment of the present invention.

Fig. 4 is a corresponding view showing the pump parts in a different relation to each other.

Fig. 5 is a diagram illustrating the pressure variations under normal stroke conditions in the fuel injection system in which the fuel pump of Figs. 3 and 4 is incorporated according to the irst regulation possibility above mentioned.

v Fig. 6 is a diagram which illustrates the pressure variations in the same system when relief is effected, in accordance with the invention, when strokes of a length above normal occur.

Figs. 7, 8 and 9 are central longitudinal sectional views through a fuel pump very similar in most respects to that of Figs. 2, 3 and 4, but with arrangements for the automatic increase of fuel supply when stroke length is below normal as well as for decrease of fuel supply when stroke length exceeds normaL ln contrast with the disclosures of Figs. 2, 3 and 4 and Figs. 7, 8 and 9, Fig. 10 is a sectional view through an accumulator type pump in which, however, the regulation is still effected through coaction between the pump plunger and pump discharge Valve.

Fig. 11 is a diagrammatic view similar to Fig. 2, but illustrating an embodiment of the invention in which mechanical unseating of the fuel pump discharge valve is replaced by a special construction of fuel pump barrel and plunger.

Figs. 12, 13, 14, 15, 16 and 17 illustrate the structure and mode of operation of a modified pump construction in which the fuel pump plunger controls a small vent hole leading back to the suction chamber of the pump, maintaining this hole continuously closed as long as the machine is not exceeding its minimum stroke, but progressively opening (uncovering) it for increasing periods as the stroke is increased to normal and for even longer periods if and when the stroke increases toward maximum, Figs. l2, 13 and 14 being respectively central longitudinal sections showing the fuel pump plunger in a much retracted position, in a position in which the machine is not exceeding its minimum stroke, but is about to do so as its stroke length builds up, in a position corresponding to that which exists when the machine is working a stroke on the order of normal, and in a position when the machine is working a stroke on the order of maximum; Fig. 15 being a perspective of the fuel pump plunger, Fig. 16 a central longitudinal section through the cylinder and (casing of the fuel pump on the same plane as Figs. 12, 13 and 14, and Fig. 17 being a central longitudinal section at right angles to the plane of Fig. 16.

Fig. 18 is a longitudinal section through an injection pump of the accumulator type constructed according to the principles of the embodiment of Figs. l1 to 17.

It will of course be understood that the present invention may be practiced with other forms of free-piston compressors than the one which will be now described for the purpose of illustrating a setting of the invention from certain of its aspects, and for illustrating the invention in its more comprehensive, motor-compressor aspect in a preferred embodiment.

For a more detailed illustration of the motor-compressor mechanism illustrated in Figs. 1 and 2, reference can be had to my copending applications Serial No. 272,019, led February 18, 1952, now. Patent No. 2,775,398;

Serial No. 285,472, filed May 1, 1952, now abandoned@ of which application Ser. No. 634,472 is a continuation now Patent No. 2,841,322 issued July 1, 1958 and Serial No. 297,745, filed July 8, 1952, now Patent No. 2,755,988.

Now referring iirst to Fig. l, it will be noted that there is shown a motor-compressor comprising twin motor cylinders 1 and 1 which have their axes at least substantially parallel and which are supported by a frame F. The motor cylinders 1, 1', have reciprocable in them in counterstroke relation to each other pistons 4, 5 and 4', 5 which control scavenging ports 2 and exhaust openings 3. The four pistons, formed as differential pistons, are coupled in pairs (4 with 4 and 5 with 5'), each pair by a double-armed rocker 6, 7 (otherwise stated: centrally pivoted levers), the iirst pair by the rocker 6 and the second by the rocker 7, so that the outward, working strokes of the pistons associated with the cylinder 1 occur with and indeed compel the inward, compression, strokes of the corresponding pistons on the cylinder 1 and vice versa. The doublearmed rockers 6 and 7 are pivoted respectively by shafts 3 and 9 in the frame F, and they have in fixed i relation to them gear segments 1t) and 11 which swing in the same angular directions as their respective rockers. These segments, through their mutual engagement, pre- Ventthe piston systems from getting out of synchronism with each other. The outer ends or arms of the doublearmed rockers 6 and 7 are designated 21 and 22. The outer ends of each arm are provided with bearings 24 surrounding pins 25 which are in turn supported in box elements 26, and these box elements are slidably arranged in guides 27 extending transversely to the several pistons and providing for guided movement of the boxes' 26 transversely of this postons as the latter reciprocate. Compressor cylinders 32 and 33 and 32' and 33 are diS- posed coaxially with the motor-cylinders 1, 1 and are open at their ends toward the engine cylinders, but closed at their other ends by cylinder heads 34, 35 and 34', 35. These cylinder heads carry and house the suction and discharge valves 36 and 37 for the compressor cylinders. Two receivers 33, suitably connected in communication with each other, are shown, and compressor pistons 39, 4@ and 39', 413', reciprocable in the cylinders 32, 33 and 32 33 pump fiuid. Twin fuel injection pumps (see Fig. 2) are shown at 41 and 42, and may be driven as from the rocker shaft 8 in any suitable manner, as by a rocking cam C. Conduts 43 and 44 conduct fluid from the fuel pumps 41 and 42 respectively to suitable nozzles, which are illustrated only by the circular bodies designated N and the reference characters 45 and 46, one nozzle associated with the motor-cylinder 1 and the other with the motor-cylinder l'.

The fuel injection pumps 41 and 42 are of the socalled port control type. Such pumps control their ports by means of a spiral edge on the pump plunger, and the plunger can be turned in the pump barrel while pumping, thus changing the portion of the plunger stroke during which the ports are covered, and the fuel is forced towards the nozzle.

The fuel oil supply system to the pumps, being conventional, needs no illustration.

The cylinders 1 and 1 are, as above noted, provided with connections N for receiving the injection nozzles and, in addition, one of the cylinders, herein the cylinder 1, is provided at its midpoint, longitudinally, with a chamber structure P communicating with the mid-point of the motor cylinder bore, and having suitable firing mechanism (not shown) associable with it.

To start the motor-compressor, the pistons 4, 5, are

brought in any suitable manner to their mutually adjacent dead center position, and a small cartridge, provided is ignited, the pistons are forced, apart` in. cylinder 1,..-

and compression is effected in cylinder l, tion of fuel into cylinder l as the pistons 4', :s compress the air between them in l the cylinder A will result in an explosion occurring in cylinder 'i' and a forcing so that injecapart of the pistons 4 and 5 and a concurrent driving 5 together again of the pistons d, 5. i e the pistons uncover the exhaust and sca'.7V ports which they control exhaust and scavenging cmatically elfected as will be later described; A n tle compression strokes of the motor pistons. th, new charges l() e upon fuel ed to take the control of apparatus which will row c in some detail, much of which is described in applM ion S rial No. 285,472, above referred to. The e enging arrangements, their operation, al operate will be later described e:

As previously indicated, the gine cylinders li and l', 2O ing portions of opposed-piston, L adapted to have fuel oil pumped to the actively by the pumps Lil and 42. FThe constr ion of these pumps will be later described in aporo i te detail and incorporate provision for automatic v.. i of instant of fuel delivery and the duration of the variation being effected in a ge manner, as by reciprocation of s rotates the pump plungers on their as to vary the fuel delivery of th maximum and Zero. By the prep slanting control edge of the pump practically any rate of fuel dspla eA as a function of the angle of of h pump plungers. ln view of the full diccuss in .aerial No 285,472, above referred to, ther ne? discussion of this here, and it may s., purposes of illustration, that the rack as a function of receiver pressure of a receiver pressure responsiv mechanism K1, and that the cr i plunger will be so formed and the mcy" rack bar R be coordinated with receiver nre rure in such a manner that when receiver pressure sure gauge there is supplied pro to be burned to effect starting; when rco.-. at 14.7 pounds gauge there is supplied the of fuel to be burned to el'lect tl e com.: charge against that pressure of the 'f' in; and as receiver pressure i. fuel injected is properly increamd. tity of fuel injected at each l for the work of compression of the sca n t supplied to the motor, as well as for the compresion and discharge of air taken into the compressor cyli s.

Another receiver pressure resf ice Ks controls the quantity of air delivered.. rn'essure responsive device, which becomes oe as a coitrol as soon as receiver pressure e l lower limit of the designed operati imple, 7 @0 atmospheres gauge, does so th impulse givers i, l which may be of v tue type of construction as the pumps di, .e normal operating range, say from 7 atm atmospheres gauge, the device l piston mechanism as shown-ad delivered by the compressor all mum dov/n to Zero delivery, if re' tinues to rise, as might occur continued. The impulse giver arranged side by side. one above adapted to be caused to give th ir tion by suitable cam actuating C. 41, 42 and the impulse givers l, o rc l ly actuatedbyv cams C and C', each, as shown7 a double cam,

are.

mounted respectively on the shafts 8 and 9. s in thf ciprocated in rhythm with the motor-compressor piston,

with which it is coordinated and moving in a bore in a cylinder which is provided for it. The shape of the control edge is determined empirically, in connection with the mechanical coupling for the control rod of the` fuel pump, so that for each load stage of the compressor the work output of the motor and the work absorbed by the compressor are in equilibrium.

During each reciprocation of its pistons the impulse givers I and l produce hydraulic impulses which areused to control lingers cooperating with the compressor suction (inlet) valves in such a way that the suction valves are held open for a smaller or larger portion of the compression strokes of the compressor pistons 39,. 4t) and 39', 44B. Each of the impulse givers acts simultaneously on two linger systems', one associated with each of the alined compressor cylinders of a pair. In application Serial No. 285,472, above referred to two different possible means for electing dilerent degrees of unloading are illustrated. In this present application but one will be described for purposes of illustration, and it will correspond generally to the second means disclosed in the earlier tiled case mentioned.

The impulse givers I and I' each comprise, as shown in Pig. 2, a cylinder 50 connected with a supply space 5l by a port not shown in Fig. 2 but shown in Fig.y 6 of application Serial No. 285,472, above referred to, to which supply space a hydraulic fluid is conducted from any suitable reservoir (not shown), said cylinder 5@ containing a plunger 53 having a control edge 54 generally helically extending about its periphery at its working end. The impulse giver plungers are actuated in turn by the cam C and are adapted to be rotated by a rack. bar R under the control of the pressure responsive device K2 to change the timing of the fluid impulses. The cylinder Si) of the impulse giver I is connected by conduits with cylinder and piston mechanisms which keep open the inlet valve associated with the cylinders 32 and 33, and the impulse giver I' is similarly connected by conduits with cylinder and piston mechanisms which keep open the inlet valves of the cylinders 32 and 33. These conduits are numbered 58 and 59 in the case of impulse giver l and 53 and 59 in the case of impulse giver I. These last cylinder and piston mechanisms,l

numbered 6h, actuate finger mechanisms 61 which arerv arranged to hold inlet valves open and to have their movements suitably limited as described in application Serial No. 285,472, above referred to. To provide fornecessary maintenance of the inlet Valves open during a portion of the discharge strokes of the compressor pistons, an accumulator A is associated with each conduit 53, 58, and comprises a chamber forming member 63 in which a spring 64 acts to press a septum-forming. member 65 in a direction to minimize the volume of uidl in the chambers which communicate with the conduits 53, 53. The accumulatore A, may use diaphragms, bellows, or any other desired equivalents of pistons to minimize or prevent uid leakage.

The outward (pumping) movements of the pistons or plungers 53, are, in the arrangement shown, coordinated with the suction strokes of the compressor pistons. ln other words, the movements of the plungers in their cylinders occur during the suction strokes of the compresso:- pistons. The oblique control edges 54 determ'nc` the beginning of lluid delivery. The outwardly moving plungers at first force fluid from their cylinders back into the supply space and then, when the control port is covered-earlier or later depending on the amount of plunger rotation-by the slanting control edge on the plunger, fluid delivery to the conduits 58 or 58 commences and the finger operating cylinder and piston mechanisms are actuated to hold theinlet valves in open-- mechanisms reachl the limits of their operating movement, the iluid delivered by further plunger movement is stored in the accumulator-s. Delivery and storage in the accumulators of fluid continues until the cam reaches its limit of swing, and upon reverse movement of the cam the system still remains under the pressure resulting from the provision of the accumulators until the latter are empty. Only then do the inlet valves close. The inlet valves close at the moment the slanting control edge uncovers the control port. The plungers continue inward movement in their cylinders, and the space being enlarged by inward movement of the plunger is lled from the supply space until the dead position is reached.

Further details with respect to this mechansim may be had by reference to application Serial No. 285,472 hereinabove mentioned.

As previously noted, the adjustment of the fuel supply to the work of compression and discharge of the air (which is dependent on the receiver pressure), and of the quantity of air to be handled, are obtained by giving a suitable form to the fuel-pump control-edges and to the control-edges of the impulse givers controlling the quantity of air delivered, and rotating the plungers of these devices on their axes.

Pressure responsive device K1, as above pointed out, is a device acting between p.s.i.g. and the lower limit of the designed pressure range, and it consists of a cylinder 66, a piston 67 having a piston rod 68, and a spring 69. 70 represents the point of pivotal connection of the piston rod 68 with a two-armed lever 71, which is connected, on the one hand, at 72, with the regulating rack R of the fuel pumps 41 and 42, and, on the other hand, at the articulation point 73, with the regulating rack bar R' of the impulse givers I and l which control the quantity of air pumped by the compressor. The pressure responsive device K2 acting over the pressure range between the lower and the upper designed operating pressures consists of a cylinder 74, a piston 75 having a piston rod 76, and a spring 77 suitably tensioned to cause it to commence to yield only when the lower rated pressure (as above explained, for illustration, 7 atmospheres) is exceeded. (It may be made responsive to the excess of receiver pressure over a predetermined pressure, by the use of a suitable relief valve permitting only the excess to pass it.) Due to the high spring tension and the relatively small effective pressure, the active range of this device is but small. It transmits, via a lever '78, pivoted at 79 and acting on the control element R' at the other end of the latter, adjustments to the regulating-rod R necessary for the regulation to be accomplished between zeroand full-load. 80 and 81 are pressure lines connecting the devices K1 and K2 respectively vwith the receiver.

It will be understood that with twin pumps and twin hydraulic impulse givers the elements R and R might be duplicated, each pump and each impulse giver having a control rack individual to it and those of each pair being' then concurrently actuated. This duplication, however, is unnecessary.

The symmetrical arrangement of the fuel pumps and impulse givers makes it requisite that the cams which actuate them be arranged with their angled control surfaces facing towards each other.

The positions of the parts in Figs. l and 2 correspond to the conditions present before starting of the compressor. With rising receiver pressure, the piston 67 moves, against the pressure of the spring 69, upwardly in Fig. 2, While the piston 75, owing to the considerably higher initial tension of the spring 77, remains at first at rest. The piston 67, moving upwardly, displaces, through the lever 71, swinging about the then stationary point 73, the regulating rod R, in accordance with the increasing work of compression, toward full load position, which is reached at the upper position of the piston 67, corresponding to the lower limit of the designed normal Pressure range. If the receiver pressure continues to rise further, the piston 75 commences to move down wardly, and to displace, through the rack bar R', which thereupon moves upward, that is, in the direction of zero air delivery, and through the lever 71, which is now swinging about the now stationary point 70, the regulating rod R of the fuel pump downward, that is, toward no-Ioad running position.

Referring now to Figs. 2, 3 and 4 it will be noted that the pump 41 (and a like description applies to the pump 42) comprises a plunger 91 reciprocable in a bore 92, in a pump cylinder member 93 which is mounted in a body 94, in which there is a circumferentially extending chamber 95 in which liquid fuel is maintained under an appropriate pressure. The chamber 95 is communicable through an inlet port 96 with the bore 92. A discharge valve 97 is arranged in a head structure 98 of the pump, and when unseated places the cylinder bore 92 in communication with a delivery conduit, for example, the conduit 43 leading to the nozzle 115. The plunger 91 has a groove 190 surrounding it near its working end which communicates through a longitudinal peripheral slot 102 with the end of the pump plunger. The end of the pump plunger is progressively cut away circumferentially, with the result that there is a cutting away helically of the peripheral portion of the pump plunger which lies toward the working end of the latter from the groove 100. The quantity of uid displaced by the pump plunger is variable by rotating the plunger on its axis. Until the inlet port 96 is closed, no pumping of iluid past the discharge valve 97 takes place, instead, the lluid flows freely through the slot 102 and groove 109 back to the inlet port and the chamber 95. lf the pump Vplunger isrotated to a proper relative position with respect to the inlet port 96, fluid will be displaced from the time when the inlet port is closed on the outward movement of the plunger 91 until the groove 109 comes into communication with the port 96. Since the groove is of uniform past the discharge valve 97 always takes place at the same point in the pumping stroke of the plunger 91, but

the amount of fluid displaced may be varied by rotation of the pump plunger on its axis, from zero to a predetermined maximum. A rotatable sleeve 195 surrounds the pump cylinder 93, and has a portion 196 which surrounds a reduced portion 197 of the pump plunger 91. The sleeve portion 1416 is longitudinally slotted parallel to its axis at each of its opposite sides, and a crossarm 108, xed to the reduced portion 197 of the plunger 91, is reciprocable in the slots. A suitable spring 199 normally maintains the pump plunger in retracted position, i.e. pushes it in the direction in which it travels during its suction stroke. A reciprocable body 11G, carrying a freely rotatable cam contacting element 111, is adapted to be moved by the cam C in a direction to effect its movement, and a resulting movement of the pump plunger 91, in a direction to eiect a pumping stroke. The sleeve is surrounded by and has secured to it a pinion 114 with which the fuel rack bar R engages, and the amount of lluid displaced by the pump on each working stroke is deter-mined by the position of the rack bar R. One control of the positioning of the rack bar has been hereinabove described, but it will be understood that the rack bar may have its position varied in accordance with the load, or in accordance with the speed of the compressor through well-known connections with a speed responsive device.

It will be appreciated that the oscillation of the cam C varies directly with the oscillation of the arm structure 6, and the oscillation of the latter is determined by the length of the strokes of the pistons 4 and 4i. If there is any overstroking (stroking between normal and maximum) of the pistons 4 and 4', the cam will be oscillated through such an arc that the pump plunger 91 will also' overstroke. It may also be noted, for its relevance to the 4embodiment of Figs. 7, 8 and 9, that if strokes of less.,4

the controlling edge E on the moving pump plunger 9i exposed the inlet port 'v6 and thereby connected the working space of the pu'np through slot ltlB and circumferential groove t'S-tl w1 the suction space 95 cf the pump.

The present embed ent takes advantage of the overstroking of the fuel pump plunger which attends overstroking of the engine-compressor pistons to correct the unstabilization as it occurs. lf any overstroking of the fuel pump plunger be ca sed to reopen the pump discharge valve after the end of fuel displacement by the pump plunger 'out before the end of the pumping stroke, there may he a release of duid from the conduit system leading to 'the nozzles with a resul 'ng reduction in the quantity of fuel delivered to the engine cylinder and a reduction in the energy provided upon the immediately succeeding working stroke ofthe engine pistons. To effect such a reopening of the discharge valve of the pump there is provided means between the pump plunger and the discharge valve for causing overtravel (travel over nor` mal) of the plunger to force the discharge Valve again off its seat, and while such means may assume different forms and may, for example, be fon 1ed on or carricd by either of the pump plunger or the cylinder end ofthe discharge valve, it is shown in 7Eigs. 3 and 4 as a projectie. pin portion l2@ on the upstream end of the discharge valve, of sucl` that any material overstroking of the fuel pump plunger will 4ise the discharge valve from its seat, and vent back past it to the pumping space, through the grooves on the pump plunger and the port, some of the fu l which not yet been discharged through the fuel inje 'on nozzle.

Fig. 5 shows an injection leisure diamam corresponding to a particular load cv .on and wherein neither the current nor the :ding motor compression stroke overrun its normal rr'he initial pressure ,nb-

length.

since for this diagram no prior relief is assumed to have taken place-approaches closely to the pressure which exists at the closing of t' e i eetion valve. p0 is the injection valve op `ing pressure. .f5 is the actual time during which the pum. displ ces fluid and tt the total injection time. The erf-injection, that is the injection period after the conclusion of the fluid pumping period, is a phenomenon which, if properly controlled, is genorally advantageous with free-piston machines. lt has its cause in the ccmpressib of the fuel, may be augn ented by the provision of an accumulator if desired. it is further infiuenceaole by alternation in the design characteristics of the injection system.

ln connection with the foregoing illustration of the first embodiment of the invention herein described in detail, the aft`- jection presents the further advantage and pos lity that a 'tiated before cessation of injection through oi; a work reducing effect on the very motor stroke which is taking place, whereby a substantially uniform operation of the machine is accomplished. Simultaneously, however, tue relief in accordance with the extent of the overstroke reduces the initial pressure pb in the injection system and effects thereby, with a constant pumping stroke of the pump, a reduction in the Volume of fuel injected. Also on the next working cycle the quantity of fuel driven out of the injection system past the lifted discharge valve in accordance' with the reduction in pressure must be made up out falta: ich.

of theV quantity of fluid displaced by the pump and is not" just after the plunger reaches a position corresponding to` norrnal7 stroke. As a result, this embodiment exercises its function of opening a passage for the return of fuel from the line d3 to the nozzle only during overstroking. lf the thrust pin or projecting pin portion be provided of such length that it is engaged by the pump plunger as soon as the plunger stroke grows beyond its minimum length, a valuable further control is obtained, and Figs. 7, 8 and 9 may be noted in connection with another embodiment of the invention in which this modied arrangement is present.

ln this embodiment the device works in both directions so-to-speak, that is, it diminishes the injected amount of fuel upon overstroke, hut it also increases it beyond the normal amount in case of understroke.

The amount of fuel injected will be, at minimum stroke, approximately 110% of the fuel consumption at normal stroke, and at maximum stroke the amount of fuel injected will be about of the amount at "normal stroke.

As in Figs. 7, 8 and 9, the pump construction in general is the same as is disclosed in Figs. 2, 3 and 4, and the major difference resides in the lengthening of the projecting pin portion Etf/Ztl', the same reference characters can he used on Figs. 7, 8 and 9, with the exception noted, as in Figs. 3 and 4. With this arrangement, the amount of injected fuel is increased in the case of understroke (stroke between minimum and normal), as well as diminished case of overstroke. It will 'ne understood that, for the same engine-compressor, loads, and strokes, with the discharge valve materially open in the normal stroke position of Fig. 8, something needs to be done to insure the proper amount of fuel injection at the normal stroke, that is, if there be a greater opportunity for the return of fuel from the line to the nozzle provided in the normal stroke position of the plunger, the dis'- placefment of a somewhat greater volume by the pump plunger at normal stroke may be necessary. lf it is not desired to change the pump dimensions (though this would of course be possible) a rotary adjustment of the pump plunger to effect a slightly earlier initiation of the pumping of fuel may be desirable.

This might make a slight difference in actual practice in the appearance of the right-hand end of the pump plunger in Figs. 7, 8 and 9 from the appearance in Figs. 3 and 4, but it is believed unnecessary to show' this' in Figs. 7, 8 and 9.

ln any event, in Fig. 7, illustrating the minimum stroke position of the pump plunger, it will be appreciated that as soon as this minimum stroke is exceeded there will commence an initially very small but, as the pump stroke increases, gradually increasing, opening for the return of fluid. As with the pump plunger in normal position as shown in Fig. 8, it will be appreciated that a larger amount of fluid will be returning from the nozzle line than is taking place in Fig. 7, it will be evident, hearing in mind that even in 7 the positive displacement of huid 'oy the pump plunger has ceased, that a greater net quantity of fuel will be passing through the nozzle the stroke is below normar to bring the stroke up to normaL As therelationships which exist betweenv the maximum stroke ofiig;

' normal stroke and maximum and the normal" stroke of Fig. 8 will be readily understoodfrom the description of Figs. 3 and 4, it is unnecessary to go into detailed discussion of conditions between stroke, for it will be evident that as the pump plunger increases its travel from normal to maximum travel, there will be an ofi"- setting return of increased quantities of fuel which will cause overstroking to be overcome.

It will be understood that the invention may also be practiced with an accumulator-type pump, so far as having a discharge valve moved mechanically off its seat by a pump plunger is concerned, and Fig. l is included to show how this could be accomplished. The general arrangements in Fig. l0, so far as the pump plunger 91 and the pump barrel 93 are concerned, are essentially the same as in preceding embodiments. The casing 94 is somewhat different in proportions in order to accommodate in a bore 12S a different arrangement of parts. 1t will be noted that a block 126 fitting the bore peripherally engages the head end of the pump barrel 93. This block is traversed by a through port 127, and houses, in a bore 128, a valve element 129 which is adapted to engage a seat 130, through which a passage 131 opens into communication with the head end of the pump barrel. The valve 129 has a projecting stern portion 133 engageable by the pump plunger in a manner corresponding to that in which the stem or pin portion 126 of Figs. 7, 8 and 9 is engaged. The valve is hollow, and is normally seated by a spring 1.34 received within it. The wall of the valve is traversed by ports 135, which connect the hollow interior of the valve with an annular groove 136 in the block. When the valve is unseated the interior of the valve and the space to the right of the valve in Fig. l0 are placed in communication with the right-hand end of the bore 92 of the pump barrel through the port 131, the space around the seating portion of the valve 129, the groove 136, the ports 135 and the interior ofl the valve, and the bore 92 then is connected with a conduit 138 formed in a connecting element 139 which is provided at its opposite end with a threaded connection 140 by which it is adapted to be attached to a nozzle line. The passage 138 is connected at its end remote from the valve 129 with a cross passage 142. one end of which communicates with a plunger 143 mounted in a bore 144 and normally pressed against a shoulder 145 surrounding the adjacent end of the cross passage 142 by a preloaded spring 146, which exerts an appropriate heavy pressure, as for example, but without limitation thereto, a pressure on the order of 2800 pounds per square inch.

It has previously been mentioned that the block 126 is traversed by a through passage 127. This communicates at ils end remote from the bore 92 with a passage 150 formed in a tube 151 received in a bore 152 in the member 139. The tube 151 is not slidable in the bore 152 and does not fill the full length of the bore, with the result that a chamber 153 constituted by the righthand end of the bore 152 is provided, and in this chamber 153 there is reciprocable a valve element 154 having a reduced end S of such length that whenever the valve is spaced from a seat 156 there is communication between the end of the cross passage 142 opposite the plunger |43 and a passage 157 which is connected with the fuel injection nozzle. lt will be evident that when the valve 154 is in its right-hand position it seals off communication between the cross passage 142 and the passage 157, and the annular area 158 which surrounds the reduced portion of the valve provides a shoulder which is constantly subjected to the pressure which exists in the cross passage.

By reason of the construction so far described it will be appreciated that, during the displacement of fluid by the pump plunger 91, the valve 154 is forced to a position in which communication between the passage 157 andthe cross passage 142 is interrupted, and accordngly the fuel which is displaced past the discharge valve 129 passes through the passage 138 and the cross passage 142 and displaces the plunger 143 against the force of the spring 146 and is stored under pressure in a chamber formed at the upper end (as viewed in Fig. l0) of bore 144 by the downward displacement of plunger 143 ready for delivery to the fuel injection nozzle as soon as the pressure inthe chamber 92 drops, as occurs when the port is uncovered, and then the spring 146 forces the plunger 143 to discharge the fuel from the chamber formed in the upper end of bore 144 through the cross passage 142 and the chamber 153 into the passage 157 and the connection from the threaded end to a fuel injection nozzle. Evidently the valve 154 will be maintained in its left-hand position so long as fuel is being displaced from the chamberformed at the upper` end of bore 144 and this will be so even though a portion of the fuel previously displaced past the valve 129 will be permitted to be returned around that valve when the same is unseated through the engagement of the stem 133 by the end of the plunger 91. It will be evident that the relation of the projecting stem portion 133 to the plunger 91 may be made either as in Figs. 2, 3 and 4 or in Figs. 7, 8 and 9, and accordingly it is not necessary to describe again the manner of control which has heretofore been explained with constructions in which a valve directly controls the delivery of fuel to the nozzle, for so far as the venting back of fue] is concerned the arrangement of Fig. 10 may operate in the same manner.

Before turning to a rather substantially different embodiment of the general invention a few further remarks with respect to Figs. 7, 8 and 9 may be Worth-while. It

`will be understood that in the case of each of Figs. 7,

8 and 9 the actual amount of fuel displaced by the pump l plunger will be the same. This naturally follows from the fact that the effective delivery stroke is the sarnev in each case. In Fig. 7 the plunger speed during de'ivery is lower than in the case of Fig. 8 and still less than in the case' of Fig. 9. Therefore, the peak pressure associated with the relative position of the parts shown in Fig. 9 will be the highest and in the case of Fig. 7 the lowest, assuming that in all three cases the strokes start with the same pressure in the injection pipe. In spite of the different peak pressures the injected amount of fuel, were the check valve not to be reopened during the so-called after injection, would be the same in each case.

This would be the case when delivery starts so early that at the moment the plunger hits the valve theentire injection including the after injection is passed. In this event the reopened valve relieves only to a more or less extent the pressure which remained in the system when the injector closed. The injected amount of fuel at the succeeding stroke will automatically decrease because the amount of fuel that escaped out of the system has to be replaced rst by the succeeding delivery. Actually the injection starts only early enough to end the delivery-even in case of the smallest operating strokewhile the plunger is still traveling with a speed suicient to provide a good atomizing effect. Therefore, at least for full load, with its longer after injection, there is a good chance that in the caseof normal or overstroke the check valve might become reopened before the after injection is ended. In that event the tail of the injection would be cut off affecting to a certain degree the combustion of the fluid delivered on that very plunger stroke. It may be further noted, though it is not to be understood that these figures are limiting, that ordinarily the maximum over-travel or under-travel of the pump plunger will be only on the order of .004 inch.

Instead of opening the delivery valve in the event of overstroke by a push of the plunger, the fuel pump plunger, according to the embodiment of the invention now to be described, `controls a small hole connected of. fuehthrough vthe control.. hole..184, and. that. when the. pump plunger. is koperating with maximuml stroke there is an additional return fromtheline leadingto the nozzle through thecontrolhole. Side. pressure. on the. plunger dueto the actionof uid throughthe .con-trol hole, when the-control holeis. closed, is. offsetby, the provision of. the hole. 194..

The systemof bleedingr back variable quantities-of'fuel through a plunger-.controlled control. hole, as ljust described, is also applicableto injectionv pumpsof :the .accumulator type. Suchan arrangement vis shown in Fig. 18 in which the. pump plunger162,.the,fuel supply chamber 178 and openings 170 and 171 may be :thesame as-in the modification just. described. The.` other connections withthe bore .of the pump barrel are modified as will be noted from the description which follows. Theend of the pump barrel is connected with a. passage. 200. which is closed, except during displacement 4of fluid by the pump plunger,.by amodiled .dischargeor check Valve 164', which has an elongated. stem portionv 201 terminating in a at end portion 201S adaptedtocooperate with a flat seat 2.02 surrounding the end" of the jpassage 200 remote from the cylinder of the pump. Thereis an annular space 203- surrounding-thezelongated stem portion 2011` of the discharge or check valve, and this space communicates .through apassage 204 with a' chamber 205 in which a differential-valve 206.is reciproeably mounted. The large end .of the. differential valve, is .connected by a passage` 207 with passage 2.0.0.. The small end'controls-a passage 20-8 Whichlleadsv :to a conduit 209 leading to a fuel injection nozzle. Thetcontrol port 1.84 is connected `4by a passage 210 with the passage 2.0 8 and is adapted, when its .end `isuncovered, to ventrback` fuel from the conduit 2.09 leadingto .the nozzle. The annular space 203 is also connected. lby. a vconduit y212 *with* a cavity 213 ,inl whicha plunger 214..is lreciprocable. There is a space 215 beyondI .the cavity 213 Iinto which .the head of the. plunger is movable, .and in .this.space which tcommunicates .through a port or vopening 216:.with .anaccumulator chamber217, ,there is maintained .by ang/suitable means `such .as arail pumpconnected withfa passage 218 openinginto .the accumulator-chamber 217 a static hydraulic; pressureequatl; to .the-.injection pressure. The accumulator' pressure. :determines the4 actual injection 4pressure duringthe injectionv period.' When .the pump plunger. 162 .commences vthe positive. y.displacement.goff. fuel .through .the passage 200.- the Jpressure 4ris transmitted Ithrough ,the passage v20:7,. to the 'large ,end :of .thedift'erential valv.ef206 :andV forces .the 'lat-tento. a position-finwhich iuidcannot .pass from: the ,space .203. Yto the l,passage .20.5. Continued .movement oftheplungen 1.62,.displaces fuel past .the .valve 164f..and intothe-space 203; Asathefuel cannot :pass to fthe passage ;20\81,it passes-,to the passage v212 and into cavity 213 andforcestheplunger. 214 yback `against thehydraulic. pressure: .in .the accumulator cham- '.ber. `21:7 rso that ,thecavity is xenlarged. andi-,receives I.the .fueLdisplaced by the .pumpplunger 162. Whenxthe posi- .tive displacement of. fuel .by the pump plunger .162 ceases, dueto rthe. initiation .ofy uncovering .of the .opening-117.1 as. previously described, thepressure in the ypassagez200 is .immediately dropped; `permitting thevvalve 164'k to -seat andalso .removing .the hydraulic pressure holding .the diiferential valve 206,-inr-theI-position.shownr-in jF-ig. 1:8. vUpon the removal .of v the `hydraulic Apressurezon the rlarge .diameterof the differential. ,valve 2.06 vthe vlatter-.immedi .atelveonnects;passage.20t4and .passage 20,8 andthe h ydraulic pressure in the accumulator chamber 217 ,forces the. .displacement plunger. 214 inward, .displacing fuel throughthe. passage. 2.09. leading to the nozzle. Iniection .continues until .the.displacement-plunger reachesnthe position s hovvn in. Eig.18,:. inawhich positionit .may- 'be ,IlQtedtthat a-.valve-,like .head..220...on ithe plunger .engages a seat 422,1 which. surrounds .the top of ythefcavity 213. It will be uaplqneeiated thatthe coactionofthe .pump

.bleeding .hack of .fuel .from the .fuelline .209 through the passage. 210 inY afmanner like that described with respect to Figs. 11 `to.17` and" therefore a. detailed repetition of thiscontrol is unnecessary.

From ,the foregoing description it will be apparent that the invention may be embodied in numerous forms, of which a number have been described, and that the bleed- .in g backv from -the line leading to the nozzle of a variable amount .of fuel-during portions of the stroke of a fuel pumpl plunger is present in all of the .diiferent embodiments described. It'will be evident that an advantageous .control ispresented'enabling the stabilizing of an enginecompressor in a highly advantageous manner,.in all of ythe .embodiments descr'ibeddiminishing the combustion of fuel as `the pump plunger increases its stroke from normal7 to maximumf and in Va plurality of embodiments also effecting an increased combustion of fuel as vthe stroke of the pump plungerv is reduced from normal to minimum Ltfwill'be evident that a very desirable controlifis accomplished, becauseof its immediacy, and the Ycontro-lis such that only a very small variation in length between` maximum and minimum stroke takes place, thus preventing damage to `the engine-compressor. Asother advantages are clearly pointedout in the course of the-foregoing specification no more need be said here by way ofsumma-ry.

While there are .in this application.specifically described several embodiments whiohthe invention may assume in practice, jitwill .be understood that these forms ofthe same are shownfor lpurposes o f illustration and'that the ,invention Ymay bemodifedand-embodied in various other forms -without `departing 1from its spiritor the scope .of .the appended claims.

'What is claimed is:

y1L Anjinternal .combustion engine having agcombustion chamber and' a piston movable insaid combustion .chamber with variable travel, conduit means .through which fuel is conducted yen route to saidvv combustion chamber, la fuel pump connected .todischarge fuel. to sa-id ,conduit means, said fuel Ipump having a cylinder and a plunger reciprocable in .said cylindergsaid cylinder land plunger formingz .a working chamber, a discharge valve com- Ymunicating'with said'workingchamber .andsaid conduit means and! openable by fuelymoved by said. plunger and. "heldopjen' by .movingiuefl renroute fromsaid Working chamber. to said Vcondiiitmeans during lfuel pumping yby said plunger, saidfplunger having a normal stroke in fuel pumping direction.. terminating ,short of. said discharge valve but' of such llength vthat maintenance of said dischargevalve open ceases before the. end of .such normal pumping stroke, a source ofjfuel', .means for supplying fuel from said source to the working chamber of said pump for pumping by said plunger to said uid conduit means and for establishing a connection between said :working chamber and said fuel source not later than the endof .the normal Working stroke of. said plunger, means for effecting reciprocation of said .plunger Witha stroke varyingin length with variations in travel of said piston, and'means Yfor effecting a renewed connection 4between said .conduit meansand said working chamber, in the event of substantial overtravel of said plunger inr fuel pumping direction, While such overtravel is taking place.

2.' An yinternal combustion engine having acombustion chamber and a piston movable insaid -combustionchambern/'ith variable travel, conduit means through which fuel is 'conducted Vven route tosaidcombustion ohamber,.a fuel ypumpv connected -to discharge. fuely to said yconduit means, said'fuel pump having a cylinder and aplunger reciprocable in .said cylinder, said cylinder and plunger forming a working chamber, a discharge valve communicating with said working chamber and said conduit means andopenable 'by ,fuel Amoved by said plungerandheldopen .by movingfuel enroute from said-workingchamber to saidlconduit means ,duringv fuel lpumping .by said plunger, said 'plunger having a .normalstroke in fuel pumping'direstion terminating short of said discharge valve but of such length that maintenance of said discharge valve open ceases before the end of such normal pumping stroke, a source of fuel, means for supplying fuel rom said scurce to the working chamber of said pump for pumping by said plunger to said fluid conduit means and for establishing a connection between said Working chamber and said fuel source not later than the end of the normal working stroke of said plunger, means for effecting reciprocation of said plunger with a stroke varying in length with variations in travel of said piston, and means for effecting a renewed connection between said conduit means and said working chamber, in the event of substantial overtravel of said plunger in fuel pumping direction, while such overtravel is taking place, said last recited means including means deriving its actuation from said plunger for reopening said discharge valve.

3. An internal combustion engine having a combustion chamber and a piston movable in said combustion chamber with variable travel, conduit means through which fuel is conducted en route to said combustion chamber, a fuel pump connected to discharge fuel to said conduit means, said fuel pump having a cylinder and a plunger reciprocable in said cylinder, said cylinder and plunger forming a working chamber, a discharge valve communicating with said working chamber and said conduit means and openable by fuel moved by said plunger and held open by moving fuel en route from said working chamber to said conduit means during fuel pumping by said plunger, said plunger having a normal stroke in fuel pumping direction terminating short of said discharge valve but of such length that maintenance of said discharge valve open ceases before the end of such normal pumping stroke, a source cf fuel, means for supplying fuel from said source to the working chamber of said pump for pumping by said plunger to said fluid conduit means and for establishing a connection between said working chamber and said fuel source not later than the end of the normal working stroke of said plunger, means for effecting reciprocation of said plunger' with a stroke varying in length with variations in travel of said piston, and means for effecting a renewed connection between said conduit means and said working chamber, in the event of substantial overtravel of said plunger in fuel pumping direction, while such overtravel is taking place, said last mentioned means including a thrust element on said discharge valve actuated by overtravel of said plunger.

4. An internal combustion engine having a combustion chamber and a piston movable in said combustion chamber with variable travel, conduit means through which fuel is conducted en route to said combustion chamber, a fuel pump connected to discharge fuel to said conduit means, said fuel pump having a cylinder and a plunger reciprocable in said cylinder, said cylinder and plunger forming a working chamber, a discharge valve communicating with said working chamber and openable to connect the latter with said conduit means, said discharge valve openable by fuel moved by said plunger and held open by moving uid en route from said working chamber to said conduit means during fuel pumping by said plunger, said plunger having a connection with said piston whereby its stroke in fuel pumping direction varies with piston stroke, said plunger operative on movement beyond a predetermined position in which fuel pumping thereby has ceased to effect opening of said discharge valve to engage said discharge valve and reo-pen the same to permit return of fuel from said conduit means to said working chamber.

5. An internal combustion engine having a combustion chamber and a piston movable in said combustion chamber with variable travel, conduit means through which fuel is conducted en route to said combustion chamber, a fuel pump connected to discharge fuel to said conduit means, said fuel pump having a cylinder and a plunger reciprocable in said cylinder, said cylinder and plunger forming a working chamber, a discharge valve communicating with said working chamber and openable to connect -the latter with said conduit means, said discharge valve openable by fuel moved by said plunger and held open by moving fluid en route from said working chamber to said conduit means during fuel pumping by said plunger, said plunger having a connection with said piston whereby its stroke in fuel pumping direction varies with piston stroke, said plunger operative on movement through varying distances beyond a predetermined position corresponding to the minimum stroke of said piston at which the engine will remain in operation to effect opening of said discharge valve to permit return of fuel from said conduit means to said working chamber.

6. An internal combustion engine having a combustion chamber and a piston movable in said combustion chamber with variable travel, conduit means through which fuel is conducted en route to said combustion chamber, a fuel pump, said fuel pump having a cylinder and a plunger reciprocable in said cylinder, said cylinder and plunger forming a working chamber, a discharge valve communicating with said working chamber and openable by fuel moved by said plunger and held open by moving fluid en route from said working chamber during fuel pumping by said plunger, said plunger having a connection with said piston whereby its stroke in fuel pumping direction varies with piston stroke, means associated with said plunger for controlling the amount of pumped uid into said conduit means in accordance with the load on the engine, said plunger operative on movement beyond a predetermined position in which fuel pumping thereby has ceased to effect opening of said discharge valve to engage and reopen the same to permit return of fuel from said conduit means to said working chamber.

7. An internal combustion engine having a combustion chamber and a piston movable in said combustion chamber with variable travel, conduit means through which fuel is conducted en route to said combustion chamber, a fuel pump. said fuel pump having a cylinder and a plunger reciprocable in said cylinder, said cylinder and plunger forming a working chamber, a discharge valve communicating with said working chamber and openable by fuel moved by said plunger and held open by moving uid en route from said working chamber during fuel pumping by said plunger, said plunger having a connection with said piston whereby its stroke in fuel pumping direction varies with piston stroke, means associated with said plunger for controlling the amount of pumped fluid into said conduit means in accordance with the load on the engine, said plunger engageable with said discharge valve on movement beyond a minimum stroke position corresponding to the piston stroke at which the engine will just maintain operation to engage and reopen said discharge valve to permit return of fuel from said conduit means to said working chamber.

8. A tiuid flow control device comprising, a housing having a cylinder and a plunger reciprocable in said cylinder, said cylinder and plunger forming a Working chamber, a discharge valve communicating with said working chamber and openable by uid moved by said plunger and held open by moving uid en route from said working chamber during iiuid pumping by said plunger, said plunger being operative upon movement beyond a predetermined position in which uid pumping thereby has ceased to effect opening of said discharge valve to engage said discharge valve and reopen the same to permit return of uid to said working chamber through said discharge valve.

9. A fluid flow control device comprising a housing having a chamber therein, a plunger mounted in said chamber having an end portion movable in a forward path towards a surface of said chamber. means for admitting fluid to said chamber whereby said forward movement of said plunger increases the pressure of the uid located in the portion of said chamber between said end portion of said plunger and said surface ot said chamber,

afinar-malty; closed discharge. vali/.e1comrnnniatingfwign saidzchamber portionto be movableimonewdireetiongin .response to said increased pressurer to an open position to permit. discharge of fluid from .said portion of ,said chamber, means communicating ...With-said, chamber p or tionto release saidincreased ,pressure in said chamber portion after an intermediate portionof saidjforwardpath of` said plunger has been traversed whereby'said valve can close, andr means actuated -by lsaid plunger Yupon movement of said plunger beyond sai-d intermediate portion to cause movement of; said discharge valve in said -one direction.

10. A duid now control devise Comprising -ar-hollsing having a chamber therein, a plunger mounted in said chamber having an end portion movable in a forward lpath towards 4a ysurface of saidchamber, means for adfmitting ,duid to said chamber whereby said forward vmovement of said plunger increases the ,pressure of5the fluid located in Athe portion of saidchamber betweensaid en d portion `of -said plunger and said surface -of said chamber, a normally closed discharge valve communicating with said chamber portion to be movablein one directionin responseto said increased pressure to an open position to permit discharge of fluidfrom said portion of said chamber, means communicating vwith said chamber portion to release said increased pressure in said chamber portionafter an intermediate portion ofsaid forward path ko f said plunger has been traversed wherebysaid valve -ca n close, and engageable means onsaid discharge valve engageable with said plunger upon movement of said plunger beyond said intermediate portion to cause movement ofsaiddischarge valve in said one direction.

11. A fluid flow control device comprising a housing having a chamber therein, a plunger mounted in said chamber yhaving an lend portion movable in a forward path towards a surface of said chamber, means for admitting Huid-to Saidlchamber. whereby ,Said forward .moi/ ement of said lplunger increases the-[pressure of the lu1d Alocatedin the portion of said chamberbetween .said encl portion of said plunger and said surface of saidchamber, a normally closed discharge valve communicating with said chamber portion to be movable in one direction in response to said increased pressure to an open position to permit discharge of fluid from said portion of said chamber, said plunger having a passageway extending from said end portion thereof which is registerable with said means for admitting fluid to release said increased pressure in said chamber portion after an intermediate portion of said forward path of said plunger has been traversed whereby said valve can close, and means actuated by said plunger upon movement of said plunger beyond said intermediate portion to cause movement of said discharge valve in said one direction.

12. A uid flow control device comprising a housing having a chamber therein, a plunger mounted in said chamber having an end portion movable in a forward path towards a surface of said chamber, means for admitting fluid to said chamber whereby said forward movement of said plunger increases the pressure of the uid located in the portion of said chamber between said end portion of said plunger and said surface of said chamber, a normally closed discharge valve communicating with said chamber portion to be movable in one direction in response to said increased pressure to an open position to permit discharge of fluid from said portion of said chamber, means communicating with said chamber portion to release said increased pressure in said chamber portion after an intermediate portion of said forward path of said plunger has been traversed whereby said valve can close, and means on said discharge valve engageable with said end of said plunger upon movement of said plunger beyond said intermediate portion to cause movement of said discharge valve in said one direction.

13. A fluid ow control device comprising a housing open posltion to .permit discharge of. fluid fromy said :22 having vaicylinder. therein, a p1u 1 i gr :mounted 1irl lraid. ,cylinder :harina-,an ends-Portion lmovablte in .a .forward path-towards. ,Oneendtoffsaidvcylinderrmeans `for admitting kfluid to said cylinderwherehysaid forward movement of `said 1.plunger increases the pressure of the fluid located in a chamber portion between said end portion of ysaid plunger andsaid one end of saidfcylinder, a discharge valve biased `tonormallyclose said one end of said cylinder and communicating with saidchamber portion to be movable in-responseto said increased pressure to an open position to permit discharge of -fluidfrom said chamber portion, means communicating with said chamber portion to release said increased pressure in said chamber portionvafter an intermediate portionof said forward path of said plunger Ihas been traversed wherebysaid valvefcan close, and means actuated by said plunger upon movement of said plunger beyond 4said intermediate portion. toggovercome the bias of said discharge valve.y

14. A uid ow control device comprising a housing having a chamber therein, a .plunger mounted `in said chamber 'having an end portion movable in a forward Vpath towards a surface o fsaid chamber, means for admitting uid to said chamber whereby said forward movement of said plunger increases the pressure of the yuid located in the portion o f said chamber between said end portion of said plunger and said surface of said chamber, a normally yclo sed. discharge valve located in a passageway extending from said chamber portion to be movable in response to...said increased pressure to an chamber .portion Vto a s toragemeans connected to said l.passageway intermediate its. length, another passageway 'extending `from said .chamber portion having` a control means vtherein for opening and closing said first men- `tionedrpassageway ata ;loc at ion remote from said chamber -portion and said storage; means, y'said control means being 4responsive to ,said increased pressure in lsaid chamber portion to close said first mentioned passageway, means. communicating with said chamber portion for relieving said increased pressure in said chamber portion upon predetermined movement of said forward movement of said plunger whereby said control means opens said first mentioned passageway and said discharge valve can close, and means actuated by said plunger upon said forward movement of said plunger beyond said predetermined movement to move said valve into an open position whereby fluid can ow from said storage means to said chamber portion.

15. A fluid ow control device comprising a housing having a chamber therein, a plunger mounted in said chamber having an end portion movable in a forward path towards a surface of said chamber, means for admitting liuid to said chamber whereby said forward movement of said plunger increases the pressure of the uid located in the portion of said chamber between said end portion of said plunger and said surface of said chamber, a normally closed discharge valve located in a passageway extending from said chamber portion to be movable in response to said increased pressure to an open position to permit discharge of fluid from said chamber portion to a storage means connected to said passageway intermediate its length, said storage means including means for maintaining uid stored therein at an increased pressure, another passageway extending from said chamber portion having a control means therein for opening and closing said first mentioned passageway at a location remote from said chamber portion and said storage means, said control means being responsive to said increased pressure in said chamber portion to close said first mentioned passageway, means communitioned passageway and said discharge valve can close, and means actuated by said plunger upon said forward movement of said plunger beyond said predetermined movement to move said valve into an open position whereby fluid can ow from said storage means to said chamber portion.

16. A uid ow control device comprising a housing having a chamber therein, a plunger mounted in said chamber having an end portion movable in a variable forward path towards a surface of said chamber, means for admitting fluid to said chamber whereby said forward movement of said plunger increases the pressure of the fluid located in the portion of said chamber between said end portion of said plunger and said surface of said chamber, a normally closed discharge valve communieating with said chamber portion to be movable in response to said increased pressure to an open position to permit discharge of uid from said chamber portion to another chamber, a passageway extending from said other chamber and terminating with an opening in said path at a location remote from said surface of said first mentioned chamber, a relief passageway in said housing terminatingT with an opening in said path spaced from said first mentioned opening and means on said plunger spaced from said end portion for hydraulically connecting various increasing portions of said i'irst mentioned opening with said last mentioned opening after an intermediate portion of said forward path of said plunger has been traversed.

17. A uid flow control device comprising a housing having an elongated cylinder therein, an elongated plunger` mounted in said cylinder with one of its ends movable in a variable forward path towards one end of said cylinder, means for admitting uid at a low pressure to a chamber between said one ends whereby said forward movement of said plunger increases the pressure of the iiuid located in said chamber, a normally closed discharge valve communicating with said chamber to be movable in response to said increased pressure to an open position to permit discharge of fluid from said chamber to another chamber in said housing, a passage# way extending from said other chamber and terminating with an opening in said path at a location remote from said one end of said first mentioned chamber, a port in said housing spaced from said first mentioned chamber and extending from the surface of said cylinder to a low pressure volume, and said plunger having an annular passageway on its outer surface spaced from said one end to hydraulically connect various increasing portions of said opening to said port after an intermediate portion of said forward path has been traversed.

18. An internal combustion engine having a combustion chamber and a piston movable in said combustion chamber, a fuel pump connected to discharge variable quantities of fuel to said combustion chamber whereby said piston has a variable stroke, said fuel pump having a cylinder and a plunger reciprocable in said cylinder, said cylinder and plunger forming a working chamber, a discharge valve communicating with said working chamber and openable to connect the latter with said combustion chamber, said discharge valve openahle by fuel moved by said plunger and held open by moving uid en route from said working chamber to said combustion chamber during fuel pumping by said plunger, said plunger having a connection with said piston whereby its stroke in fuel pumping direction varies with variations in said piston stroke, said plunger operative on movement beyond a predetermined position to engage said discharge valve to permit return of variable quantities of fuel to said working chamber.

References Cited in the tile of this patent UNITED STATES PATENTS 1,596,194 Lang Aug. 17, 1926 1,883,980 Lang Oct. 25, 1932 2,090,709 Steiner Aug. 24, 1937 2,090,781 Camner Aug. 24, 1937 2,435,970 Lewis Feb. 17, 1948 2,473,204 Huber June 14, 1949 

